The present disclosure relates to transfer units and image forming apparatuses.
An image forming apparatus is known in which toner images formed on respective peripheral surfaces of photosensitive drums (image carriers) of different colors for forming a multicolor image are once transferred to an endlessly running transfer belt to superpose the toner images of different colors on each other to form a multicolor toner image and the multicolor toner image is secondarily transferred to a recording medium to form a multicolor image. There is also known another image forming apparatus of a type in which toner images are transferred from photosensitive drums directly to a recording medium being conveyed by a transfer belt.
In the above image forming apparatuses, during transfer of toner from the photosensitive drums, the toner may scatter to contaminate the apparatus interior and in some cases contaminate even the back side of the transfer belt. To prevent deterioration of image quality due to unstable run of an intermediate transfer belt caused by deposition of scattering toner and other foreign matters on the back side of the transfer belt, a mechanism for cleaning the back side of the transfer belt is known.